Implant Improvement

Imagine creating a prosthetic arm or leg that moved when you thought about it, the way a real limb does in response to signals from your brain. Sounds like science fiction? Not for long. Jipeng He and a team of ASU bioengineers are working to develop such technology through a federally funded neural prosthetics project.

In any massive undertaking, however, the devil is in the details. This project is no different.

Scientists learn about brain signals by implanting electrodes into the brains of animals, such as monkeys. These electrodes record the signals emitted when the animal makes a particular movement.

Although the electrodes do not harm the animals, their brains do not welcome the implants.

“Even within 24 hours, immune system cells start to respond to these implants, attacking them as foreign,” explains Matt Holecko, a doctoral student in bioengineering. “The implants create scar tissue and eventually the electrode fails.”

Holecko is working to prevent this scarring and keep the electrodes working longer.

The main cells that respond to the implants are glial cells. Holecko visualizes these cells using confocal microscopy, highlighting a particular protein called GFAP.

Next, Holecko hopes to better model the brain tissue using software being developed by PRISM programmer Jiuxiang Hu.

He needs answers to lots of questions that only a good model can provide. “How much tissue is touching the electrode? How close is it? How does a particular reaction affect the response of the electrode?” asks Holecko.

Information gathered using the PRISM software will help Holecko understand how much the cell’s response will change the electrode’s signal.

“Once we know what’s affecting the signal we can see how to change it,” explains Holecko. “We’re trying to design a better electrode. These are all steps in moving toward the creation of better prosthetics and understanding how neural signals work.”

Better electrodes will vastly improve the process of developing effective neural prosthetics.

“We implant a monkey with electrodes and teach it to do physical tasks,” explains Holecko. “Then we record the neural signals produced during those tasks.”

At some point the monkey actually wears a virtual reality glove and glasses. He repeats the task in a virtual environment.

“Eventually, a robotic arm is used to mimic the movements,” Holecko adds. “Finally, they take away the monkey’s hand control. The signals from the brain alone move the robotic arm.” —Diane Boudreau